Page 18 - August 2023

“It’s important to know that an overhauled starter generator comes with new brushes that have been properly seated ... done through the use of specialized equipment ... ”
down before the 1,000-hour mark, I would overhaul or exchange the unit at that time. It’s important to know that an overhauled starter generator comes with new brushes that have been properly seated (contoured) to the armature. This is done through the use of specialized equipment that spins the armature without putting current to it, and it can take many hours.
Overhauls and Exchanges
If you shop around, you can find an exchange -016 for as little as $1,200. My sources in the industry tell me that $1200 barely covers the cost of changing the bearings and brushes on the core units they receive for overhaul. Keep this in mind when it comes to core charge bill-backs. If the core unit you send back needs anything beyond bearings and brushes, you will get a bill-back on that core. I remember a pair of -016s I sent in for overhaul – one needed a new end bell and the other needed its armature completely re-wound. The overall cost was double the exchange price. This is par for the course with starter generators as the rotable pool ages.
If I were to come across a low-time King Air with starter generators approaching 1,000 hours for the first time, I would recommend overhaul providing the owner could afford the added downtime. I hate to see a relatively new unit tossed into the rotable pool in exchange for one that’s been around the block many times, barely meets minimum specs, and will probably need a new armature (or more) at the next overhaul, providing it makes it that far.
The Infamous Part Number: 23085-001
The starter generator found on King Air 300s and 350s is Part Number 23085-001. It is very similar to
23048-016, but for some reason the bearings in this particular model tend to fail early. And when a bearing fails, the unit destroys itself – hence the “infamous” description.
The 23085-001 has the same 1,000-hour overhaul interval as the other units discussed, but in my experience, very few of them make it. For this reason, I always advised my 300 and 350 customers to exchange or overhaul their 23085-001 starter generators at around 600-700 hours.
When a -001 goes, it is always at the most inconvenient moment – you’re on a trip and you need to fly. You call around for exchanges only to find there are none available! Now you must search for a unit to buy outright for $12,000-$15,000.
But let’s say you find an exchange for $3,000. You need it immediately. In the crate it weighs 50-plus pounds and costs $600 for overnight shipping service. Then there’s the labor to remove and replace the unit on short notice at outcall rates. Once installed, your core unit goes back to the vendor and is found BER (Beyond Economical Repair). These days, full core value on a 23085-001 can range from $10,000-$20,000. All in all, this is a $25,000 adventure once it is over and done. So, save yourself time, money and untold aggravation by overhauling or exchanging your -001 starter generators early.
One parting shot: In the unlikely event that you have a -001 that makes it to 1,000 hours, it will likely be found BER at overhaul and you will be paying the full core value anyway. That’s just the way it is with this part and it’s one of the reasons why they are suddenly scarce when you are desperate for one.
The only time I recommend that an aircraft owner exceed maintenance requirements and do something early, is because I have seen that it will save money in the long run. I am very respectful of an aircraft owner’s maintenance dollar. I think you will agree that 3,000 ounces of prevention by early compliance is worth the 25,000 pounds of cure needed when you wait until the final hour. KA
Dean Benedict is a certified A&P, AI with over 45 years of maintaining King Airs. He owned and ran Honest Air Inc., a maintenance shop that specialized in Beechcrafts with an emphasis on King Airs. Currently, with BeechMedic LLC, Dean consults with King Air owners, operators and maintenance shops on all things pertaining
to King Air maintenance. This includes troubleshooting, pre-buys and maintenance management. He can be reached at dr.dean@ beechmedic.com or 702-524-4378.
16 • KING AIR MAGAZINE
AUGUST 2023